Switch in a resistance welding system and method thereof

Abstract

Components of an electrical resistance welding system include a DC power supply, an energy storage assembly, a switch, and an electrical resistance welding assembly configured to weld a work piece. The system may be free of any transformer which permits the system to operate in an infinite number of variable voltages between a minimum and maximum system setting. The variable voltage control permits greater operability of the electrical resistance welding system by creating a specific weld voltage dependent on parameter, such as a dimension, of the work piece that is to be welded.

What is claimed is: 
     
         1 . A method comprising:
 confirming that a switch is in operative electrical communication with a direct current (DC) power supply, an energy storage assembly, and an electrical resistance welding assembly, wherein the electrical resistance welding assembly is adapted to weld a work piece;   receiving direct current from the energy storage assembly at a first terminal on the switch;   transitioning the switch from an off state to an on state;   transferring direct current from a second terminal on the switch to the electrical resistance welding assembly in response the switch having transitioned to the on state, wherein the electrical resistance welding assembly is adapted to weld the work piece in response to receiving direct current from the switch.   
     
     
         2 . The method of  claim 1 , wherein transitioning the switch from the off state to the on state is accomplished by a semiconductor or electrical contactor. 
     
     
         3 . The method of  claim 2 , wherein the semiconductor is a transistor. 
     
     
         4 . The method of  claim 3 , wherein the transistor is selected from the group comprising a Metal-Oxide-Semiconductor Field-Effect Transistor (MOSFET), IGBT, Thyrister, GTO Thyrister, or a SCR. 
     
     
         5 . The method of  claim 1 , further comprising:
 transferring direct current through a first bank of a first plurality of semiconductors on the switch; and   transferring direct current through a second bank of a second plurality of semiconductors on the switch.   
     
     
         6 . The method of  claim 5 , wherein the first bank of the first plurality of semiconductors is electrically parallel to the second bank of the of the second plurality of semiconductors. 
     
     
         7 . The method  claim 5 , further comprising:
 transferring direct current through a source busbar, wherein a source connection on each of the semiconductors in the first bank and the second bank are electrically connected to the source busbar.   
     
     
         8 . The method of  claim 7 , further comprising:
 transferring direct current through a drain busbar, wherein the drain busbar has at least two portions, wherein direct current is transferred from a drain connection on each of the semiconductors in the first bank to a first portion of the drain busbar and direct current is transferred from a drain connection on each of the semiconductors in the second bank to a second portion of the drain busbar.   
     
     
         9 . The method of  claim 8 , further comprising:
 transferring direct current from the first portion of the drain busbar and the second portion of the drain busbar to a central portion of the drain busbar, wherein the second terminal is connected to the central portion of the drain busbar.   
     
     
         10 . The method of  claim 5 , wherein the first plurality of semiconductors of the first bank are electrically parallel with each other. 
     
     
         11 . The method of  claim 5 , further comprising:
 transferring, simultaneously, a gate voltage to each gate connection of the first plurality of semiconductors and the second plurality of semiconductors, wherein the gate voltage is controlled by a programmable logic controller (PLC).   
     
     
         12 . The method of  claim 5 , wherein the number of semiconductors in the first plurality of semiconductors is in a range from two to ten. 
     
     
         13 . The method of  claim 12 , wherein the number of semiconductors in the first plurality of semiconductors is either six or eight. 
     
     
         14 . The method of  claim 1 , further comprising:
 transitioning the switch from the off state to the on state in less than about 0.3 milliseconds.   
     
     
         15 . The method of  claim 1 , further comprising:
 controlling variable voltage from the DC power supply and the energy storage assembly with the switch.   
     
     
         16 . A switch assembly for an electrical resistance welding system, the switch comprising:
 a first terminal configured to be coupled with an energy storage assembly;   a second terminal configured to be coupled with an electrical resistance welding assembly;   at least one semiconductor that is in operative electrical communication with the first terminal and the second terminal to receive current from the energy storage assembly and selectively permit a transfer of current to the electrical resistance welding assembly in response to application of voltage to the at least one semiconductor to transition the switch assembly from an off-state to an on-state.   
     
     
         17 . The switch assembly of  claim 16 , further comprising:
 a plurality of semiconductors that are in operative electrical communication with the first terminal and the second terminal to receive current from the energy storage assembly and selectively permit the transfer of current to the electrical resistance welding assembly in response to application of voltage simultaneously to each of the plurality of semiconductors to transition the switch assembly from the off-state to the on-state, wherein the at least one semiconductor is within the plurality of semiconductors.   
     
     
         18 . The switch assembly of  claim 17 , further comprising:
 a first plurality of semiconductors defining a first bank of semiconductors;   a second plurality of semiconductors defining a second bank of semiconductors;   wherein the first bank of semiconductors is electrically parallel with the second bank for semiconductors;   wherein the first plurality of semiconductors are transistors and the second plurality of semiconductors are transistors.   
     
     
         19 . The switch assembly of  claim 18 , further comprising:
 a source bus bar that is in electrical communication with the first terminal, wherein a source connection of each transistor is electrically connected to the source bus bar;   wherein the source busbar is formed by a central plate.   
     
     
         20 . The switch assembly of  claim 18 , further comprising:
 a drain busbar that is in electrical communication with the second terminal, wherein the drain busbar is composed of a first drain busbar component and a second drain busbar component and a central drain busbar component that electrically connects the first drain busbar component with the second drain busbar component, wherein a drain connection of each transistor is electrically connected to the drain busbar; and   wherein the drain busbar is formed by a U-shaped plate, wherein a first leg of the U-shaped plate defines the first drain busbar component, a second leg of the U-shaped plate defines the second drain busbar component, and a central leg of the U-shaped plate defines the central drain busbar component.   
     
     
         21 . The switch assembly of  claim 17 , further comprising:
 a U-shaped plate comprising a first leg, a second leg, and a central leg;   a central plate located within a space between the first leg and the second leg of the U-shaped plate;   a gap defined between a perimeter edge of the central plate and inner edges of the U-shaped plate, wherein the first bank of semiconductors and the second bank of semiconductors span the gap;   wherein the first bank of semiconductors and the second bank of semiconductors span the gap below the central plate and the U-shaped plate.